This invention relates generally to a pump sprayer capable of dispensing in both upright and inverted positions, and more particularly to such a sprayer which avoids simultaneous ingestion of air into the pump chamber from the container vent passage when operating in an inverted position of the sprayer.
Known pump sprayers are disclosed in German Pat. No. 30 45 565 and in U.S. Pat. No. 4,277,001 as having an auxiliary valve assembly associated with the pump chamber to facilitate inverted spray. Such sprayers typically have a container vent passage which is opened during the piston pressure stroke to admit atmospheric air into the container to replace the liquid being dispensed so as to avoid hydraulic lock within the container by equalizing the pressure therein. In the German Patent, the container vent passage extends through a central opening in the closure cap through which the hollow piston stem extends, through an opening of the pump cylinder and into the container. A depending collar on the closure cap surrounding the central opening is engaged by the pump piston at the end of the piston suction stroke for closing the vent passage, the vent being opened by the pump piston during reciprocation within the pump cylinder.
However, when these sprayers are operated in an inverted or steeply slanted position, air bubbles entering the liquid in the container through the open vent passage during piston reciprocation are suctioned into the pump chamber through the liquid intake port which, especially for fine mist sprayers, is unacceptable. This unwanted air ingested into the pump chamber adversely affects pump priming by reducing the liquid volume of the pump chamber causing a sputtered and uneven spray and dribbles and drips from the discharge orifice at the end of each pressure stroke. And, a sufficient volume of air in the pump chamber can cause the liquid output during pumping to cease almost completely which is totally unacceptable for the largely pharmaceutical and cosmetic applications of these sprayers.
In the aforementioned patented sprayers, for example, the air vent port through which air enters the container, in an upright position of the container, is always above the liquid intake port usually located at the terminal end of the dip tube which extends to the bottom of the container. Conversely, in an inverted position of the sprayer, the air vent port which is controlled by the pump piston is below the liquid intake port such that air bubbles are ingested automatically into the pump chamber during piston reciprocation.
Another disadvantage which is apparent from the aforementioned German patent sprayer is that the liquid intake port is located relatively far from the mouth of the container so that complete removal of the liquid product from the container is inhibited during inverted spray.
Although an upwardly extending liquid intake conduit lies just below the mouth of the container for inverted spray, as in U.S. Pat. No. 4,277,001, such is made possible only for sprayers having an auxiliary valve attached external to the pump cylinder and requires, mreover, a greater effort through additional fastening and coupling components and a more complicated and laborious assembly procedure.